9900 19TH AVE SE WINCO FOODS 2025-07-29

Stormwater Management Report Everett, WA Executive Summary Site Location: The property is located at the northwest corner of the intersection of 19`h Ave SE (SR 527) and 100`h St SE in Everett, Washington. The site currently has an existing retail building with garden center and 399 parking stalls. The site was originally developed as a Home Base in 1999 to 2000. Commercial and office uses are to the east and south of the property with an existing roller rink to the north. Interstate 5 is to the west of the property. The project proposes to redevelop the existing building for commercial retail purposes on this 9.09 acre site. This site will expand the existing structure to an 114,136 SF retail store. Also included in this redevelopment are parking area, storm drainage relocation and landscaping improvements. The site has an adjacent 0.70 acre fast food restaurant to the southeast which is not a part of the redevelopment. This outlot drains onto the project site and is included in the drainage basin. The redevelopment project will not affect the storm drainage of the 0.70 acre property. This drainage report lists the design calculations and assumptions for the redevelopment of the site. Design Criteria: The City of Everett uses the storm drainage requirements listed in the "1997 Everett Stormwater Management Manual." This project will evaluate the existing and developed site conditions to comply with these requirements. Table 1 Jurisdictional Requirements Peak Run-off Control: Santa Barbara Urban Hydrograph Analysis 2-year: Match 50% of pre-developed 10-year: Match pre-developed 100-year: Match pre-developed Water Quality: Treat the 6-month storm Conveyance 25 Year, 24 Hour Downstream Analysis: Level 1: lA mile downstream Proposed Drainage System: This project proposes to use the existing network of underground pipes, catch basins, curbs and gutters to collect surface water runoff throughout the site. Runoff from paved areas subjected to vehicular traffic is treated by an existing combined detention and wetpond prior to discharge. Runoff from the roof will continue to be detained in an underground detention system. The proposed detention vault is to the north of the existing building. The vault will match the size and discharge rates as the existing 96" detention pipes. Stormwater will continue to be infiltrated from the detention system through a 6" wetland recharge pipe which runs south under the existing building. Stormwater overflow will continue to discharge to the adjacent wetland north of the project site. PACLAND 10213001 3